Keeping pool waters sparkling clean takes knowledge and diligence. Water is an essential ingredient for all life as we know it, and unfortunately, that means that many different organisms thrive in untreated pool water. Without any chemical treatment, swimming pools rapidly turn green and cloudy and pose health risks to swimmers.
Function
Swimming pool chemical treatments function to disinfect the sweat, mucus and urine excreted from bathers, the bacteria and viruses introduced by them, and dirt and pollutants tracked in. The treatments also kill protozoa and prevent algae and fungus from growing on pool filters and in the water. An additional important function of chemical treatments is maintaining a balanced pH level in the water. The Centers for Disease Control and Prevention says that ideal pool pH falls between 7.2 and 7.8. Lower, more acidic, pH levels hinder disinfection and both lower and higher levels cause irritation in swimmers.
Substances Used
Pool workers frequently use chlorine as a disinfectant in pools. It is available as a pure gas or mixed in a granular powder or liquid form. Bromine has similar disinfectant qualities as chlorine and is useful in spas and hot tubs because of its stability in high temperatures. It tends to break down in sunlight, so indoor facilities use bromine more often than outdoor ones. Other types of pool chemicals include additives that help balance pH, such as sodium carbonate and muriatic acid. The compounds decrease and increase the pH levels, respectively.
Levels and Timing
Public pool managers frequently test pool water to determine when they need to treat them. When heavy use overloads a pool and threatens water clarity and safety, pool workers superchlorinate or shock the pool to bring the situation back under control. Superchlorination involves adding large amounts of additional chlorine to destroy or neutralize organic and inorganic substances in the water. Ideally, shocking a pool occurs after sundown, when bathers leave and temperatures fall. The chlorine concentration dissipates as it interacts with the contaminants during the night. Because heavily chlorinated pool water is hazardous, levels must decrease to between 1 and 3ppm before swimmers return.
Side Effects
Swimming pool chemical treatment cleans water, but also bothers some pool patrons. The culprits are the byproducts of the disinfection process, rather than chlorine itself.
Chloramines or chlorine compounds such dichloramine, produced from the interaction of chlorine and ammonia in the water, causes eye and skin irritation as well as the strong odor typically associated with chlorinated pools.
Trihalomethanes, produced by the interaction of chlorine with organic contaminants, tend to collect at, or just above, the surface of the water. Swimmers breathe in the substance, which causes breathing problems and lung irritation, according to Mary Pohlman, M.D., assistant professor of clinical medicine at Southern Illinois University School of Medicine and a member of the United States Masters Swimming Sports Medicine Committee, in a June 2006 article for "Swimmer" magazine.
Considerations
Swimming has health benefits associated with it, so some people just tolerate the side effects they suffer from chemical pool treatment. Well-maintained pools cause users fewer problems, as sufficient chlorine levels and correct pH balance prevent buildup of many of the irritants in the water. Swimming outside is preferable to swimming indoors for people with asthma or sensitive lungs, because ventilation helps avoid concentration of chemicals in the air. As useful as chemical treatments are in preventing disease, the chemicals themselves are hazardous materials. Pool workers must handle them with caution.
References
- CDC: Your Disinfection Team: Chlorine and pH
- "What Color is Your Swimming Pool?" Alan E. Sanderfoot; 2003
- USMS Swimmer: The Healthy Swimmer: Coping With Chlorine Reactions
- "Pasadena Star News": Excess Chlorine Release in Arcadia Blamed on Human Error
- Siemens: Swimming Pool Disinfection Techniques & Pitfalls
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